Oscillator.



PATBNTED JAN. 6, 1903.` H. SHOEMAKER.

USGILLATOR.

APPLICATION FILED N07. 10, 1902.

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No. 717,774. PATENTED JAN. 6, 1903.

H. SHOEMAKBR.

OSGILLATOR.

APPLICATION FILED Nov.1o, 1902. v No MODEL. z SHEETS-SHEET a.

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HARRY SHOEMAKER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO MARIE V. GEHRING, OF PHILADELPHIA, PENNSYLVANIA, AND THE CONSOLIDATED WIRELESS TELEGRAPII AND TELEPHONE COMPANY, A CORPORATION OF ARIZONA TERRITORY.

OSCILLATOR.

SPECIFICATION forming part of Letters Patent No. 717,774, dated January 6, 1903.

Application filed November 10, 1902. Serial No. 130,641. (No model.)

To all whom, t may concern.-

Be it known that I, HARRY SHOEMAKER, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Oscillator, of which the following is a specification.

My invention relates to wireless signaling systems, more especially those in which the message or signal is represented by electroradiant energy transmitted through the natural media.

More especially, my invention relates to the transmitting apparatus at a wireless signaling-station; and it consists of a portable freelyoscillating circuit so arranged and constructed that the natural rate of oscillations of the circuit may be varied within certain limits at will in order that the frequency of the transmitted electroradiant energy may be properly proportioned with respect to either the radiating-conductor of the transmitting-station or the receiving-conductor of a receiving-station, whereby the best effects may be produced at the receiver.

My invention consists of a portable oscillator comprising a freely-osciallating circuit including an adjustable condenser, whereby the wave length of the transmitted electroradiant energy may be varied Within certain limits.

My invention consists of a standard piece of apparatus calibrated in definite units representing a function of the wave length of the transmitted energy and so arranged and constructed for the purposes of portability that no trial or experiment is necessary when first employing the apparatus at a newly-organized station. It being known what Wave length it is desired to transmit, it is simply necessary to adjust the condenser until the indicator points to the graduation-mark corresponding with the desired wave length.

In the manufacture and construction of the oscillator herein described all connections between the several elements of the oscillating circuit are of heavy low-resistance conductors, and corresponding conductors in different oscillators have the same geometric dimensions. In fact, all the parts of the oscillator are standardized and are interchangeable in the different oscillators. Each oscillator is, however, independently calibrated.

Reference is to be had to the accompanying drawings, in which- Figure 1 represents a view, partly in section and partly in elevation, of the oscillator. Fig. 2 represents a top plan View of the oscillator. Fig. 3 is a horizontal section of lthe oscillator, showing some parts in plan View. Fig. 4 is' a diagram of the circuit arrangements employed during calibration.

In Fig. l, l represents a box or casing, preferably of insulating material, such as wood.

2 and 2 represent the plates constituting the armatures of an adjustable condenser whose dielectric is constituted in part by air and in part by the glass plates 3, which, as shown in Fig. l, extend to the full height of the inside of the casing l.

4 represents a support extending transversely of the casing 1, and to which are electrically and mechanically connected the armatures 2, consisting of self-supporting copper plates. At the ends of the member 4 are enlargements,which are machined,so as to slide readily and smoothly in the guideways 36 36, secured on the inside of the casing 1 on the side walls. By this arrangement the armature 2 has a telescopic movement with respect to the stationary armature 2', also constituted of self-sustaining copper plates which are fixed and electrically connectedwith each other and by means ot' the conductor 24 with the binding-post l2.

5 is a screw-threaded rod which engages a threaded hole in the member 4. At the opposite end of the rod 5 is a collar or head 33, by means of which the rod 5 is prevented from having longitudinal movement, but is free to rotate.

9 is a bracket through which extends the vertical rod 8, carrying at its lower end a beveled gear meshing with the beveled gearwheel 6, secured on the rod 5.

10 isa .collar on the rod 8, which, along with the collar on the beveled gear 7, prevents the rod 8 from having longitudinal motion.

11 is a handle outside oi the casing 1 and secured to the rod 8, whereby rod S and rod may be rotated, causing the armature 2 to move with respect tothe fixed armature 2 of the adjustable condenser.

3l is a flexible copper ribbon affording electrical connection between the armature 2 and the binding-post 12. When the armature 2 is moved toward the right, the ribbon 3l bows downward toward the bottom of the casing.

32 is ahorizon tal projection serving to prevent the ribbon 31 'from bowing upwardly.

Extending from the binding-post 12 is the conductor 23, communicating with the binding-post 23', forming one terminal of a coil 22 of heavy conductor and very few turns, about two or three in number. The other v end of" the coil connects with binding-post 21 and thence by conductor 21 with the metallic bracket 1G. vEetween a pair of brackets 1G and 1G is situated a spark-gap 19, whose terminals are at the ends of rods adjustable by means of thumb-screws 2O and 20. This spark-gap 19 is situated within a chamber 18, of glass oi other material,containing a gas under pressure. Plates 17 17 form the end Walls for the chamber 18. A conductor 15 leads from bracket 16' to the binding-post 14 and thence by the metallic bracket or angle 13 with the binding-post 12. From this it is seen that the adjustable condenser, coil 22, and the spark-gap 19 are connected in series, forming an oscillating circuit whose rate of vibration depends upon the inductance and capacity of such circuit and maybe varied by the adjustable condenser.

The coil 22 is mounted within a box or casing 28 upon the top of casing 1, and within this boX and in inductive relation with respect to the coil 22 is the winding 25 of relatively greater number of turns than in coil 22, the terminals of said coil 25 being joined to the binding-posts 2G and 27, mounted upon the top of the box 2S. ln operation a conductor joins the post 2G with an earth-plate E, while the aerial conductor A of the transmitter is joined with binding-post 27. These windings 22 and 25 constitute, respectively, the primary and secondary of a transformer by means of which electrical oscillations of a frequency dependent upon the constants of the oscillator-circuit are forced in the aerial circuit. The energy is derived from the secondary of the transformer or induction-coil, the terminals of such secondary being joined to the brackets 1() and 1(3, the operators key being, as usual, in the primary of such induction-coil or transformer or at any other suitable point.

With the armatures 2 and 2 in the relative position shown in Fig. 1, the capacity of the adjustable condenser is at its maximum, and in consequence the natural period of the oscillator is at its maximum, and the frequency As the armature 2 is moved in either direction the point 30 moves over the graduated scale 35, indicating either the frequency of the oscillator corresponding to a certain position ot the armature 2 or, it desired, indicating the Wave length, which is a simple function of the frequency. 1n practice, however, it is desired to calibrate the scale to indicate quarter wave lengths-that is, heights of the aerial receiving-conductor. For eX- ample, if it is desired to transmit to a station whose receiving-conductor has a length of one hundred and twenty feet the handle 11 is turned until the indicating-point 30 comes opposite to the graduation-mark on 120. Armature 2 is then in such position and the capacity of the oscillator-circuit is then such that the length of the wave transmitted will be four hundred and eighty feet.

To calibrate the oscillator, it is connected as shown in Fig. 4. 'lo the brackets 16 and 1G' is connected the secondary 3S of a transformer whose primary is shown'at 39. In the circuit of this primary is a source of energy 4l, a switch or key 40, and an interrupter 41. The coil 25 of the oscillator is connected to two conductors or vanes 42 or 4S. Arranged parallel to and near these conductors 42 and 43 are the conductors 44 and 45, respectively, which are bent at right angles, as shown.

46 is a short-circuiting rider sliding upon the conductors 44 and 45, and 47 is a sparkgap whose terminals are also capable of sliding along the conductors 44 and 45.

Suppose it is desired to find the position of the indicating-point 30, so that the oscillator may be emitting a wave whose length is six hundred feet-that is, a wave suitable for transmission to a receiver whose aerial circuit is one hundred and iifty feet in length. The rider 46 and spark-gap 47 are so placed along the conductors 44 and 45 that the distanees a c or b d are one hundred and it'ty feet, and so that the distances a ef and Z) g 71, are also one hundred and fifty feet. The handle 11 is then tufned backward and forward, the switch or key 40 being closed, until the most vigorous sparking is produced at the gap 47. When the sparking at 47 is the most vigorous, the constants of the oscillator-circuit are properly adjusted for producing a wave six hundred feet in length or most suitable or transmission to a station whose receiving-conductor is one hundred and iifty feet in length. This position of the armature 2 having been found, a calibration-mark is made opposite to the pointer 30 and marked IOO IIO

F 150, or, if total wave length is desired, itis marked GOO. By the same process numerous other calibration-marks are obtained for numerous other Wave lengths. l

The conductors 44 and 45 need not be straight, but to economize space may be stretched upon grids or other suitable supports.

What I claim isl. As an article of manufacture, au oscillator calibrated as to frequency.

2. As an article of manufacture, a portable oscillator calibrated as to frequency.

8. As an article of manufacture, a portable oscillator calibrated as to Wave length.

4. As an article of manufacture, a portable closed oscillating circuit, means for changing the natural period of said circuit, and means for indicating the resultant Wave length.

5. As an article of manufacture, a portable HARRY SI-IOEMAKER.

lVitnesses:

ALICE T. BURROUGH, EMIL LENERT. 

